This invention relates to apparatus for treating liquids to reduce the effects of hardness and to a cleaning device and excitation circuit therefore.
Water hardness has usually been eliminated, in the past, by a chemical process which withdraws from the water the particular hardness causing impurities. Electrical water treatment devices, such as that described in U.S. Pat. No. 2,729,859 have also been used to eliminate water hardness effects by passing the water through an electric field established by an electrically conductive fitting and an electrically conductive screen insulatively supported therein. A voltage potential applied across the housing and screen establishes the electric field. One problem with such prior art electrical water treatment devices is the accumulation of scale and other mineral deposits on the screen, which restricts water flow through the openings therein and reduces the electric field by providing an insulating coating on the screen.
Accumulated mineral deposits in a fluid system, for example in hot water tanks, boilers, water towers, air conditioners, humidifiers, dishwashers, spray nozzles, etc. are often difficult to remove, sometimes requiring an acid treatment for effective removal. Conventional water softening chemicals and ion exchange treatments, while removing the hardness causing minerals from the water, do not eliminate those minerals already deposited and accumulated in the water system.